"How do you get such a clean break all the way around that tail cone? Is that seam an engineered weak point?"
The structure failed due to overload. The frame creates a stress riser, so failure at that point is nor un-expected. In normal loading, there is not enough stress at the frame to cause a problem.
Think of a balloon. Wrap a steel band around the balloon and inflate till it is tight. Then overinflate the balloon till it pops. It will likely fail at the steel band (stress riser).
Stressed skin (monocoque construction) needs ribs, frames,stringers, and longerons to form the shape of the structure, the strength is largely in the skin.
Last edited by oleostrut; 3rd Nov 2015 at 01:07.